1. Field of the Invention
The present invention relates to the decontamination of chemical and biological warfare agents. The invention also relates to a process for removing chemical and/or biological contaminants from a breathable atmosphere. More particularly, the invention relates to a continuously self-regenerating filter system for removing chemical and/or biological contaminants from a breathable atmosphere.
2. Description of the Related Art
The threat of biological and chemical warfare has grown considerably in recent years. Highly dangerous biological and chemical warfare agents have been developed and stockpiled by several nations. Some of these potent biological agents include bacteria such as Bacillus anthracis (anthrax) and Yersinia pestis (plague); viruses such as variola virus (small pox) and flaviviruses (hemmorhagic fevers); and toxins such as botulinum toxins and saxitoxin. Examples of some potent chemical agents include blister or vesicant agents such as mustard agents; nerve agents such as methylphosphonothioc acid (VX); lung damaging or choking agents such as phosgene (CG); cyanogen agents such as hydrogen cyanide; incapacitants such as 3-quinuclidinyl benzilate; riot control agents such as orthochlorobenzylidene malononitrile (CS); smokes such as zinc chloride smokes; and some herbicides such as 2,4-D (2-4-dichlorophenoxyacetic acid).
Such biological and chemical warfare agents pose a significant risk to private citizens as well as to military personnel. For example, nerve agents are particularly toxic and are generally colorless, odorless, and readily absorbable through the lungs, eyes, skin, and intestinal tract. Even a brief exposure can be fatal and death can occur in as quickly as 1 to 10 minutes. Vesicant agents are known to burn and blister the skin or any other part of the body they contact, including eyes, mucus membranes, lungs, and skin. Biological agents such as anthrax are easily disseminated as aerosols and thus have the ability to inflict a large number of casualties over a wide area.
Known techniques for protecting humans from breathing-in hazardous substances include the use of respiratory masks, or gas masks as well as vehicle, room and building air filters. Protective masks are currently used by the military for protection against chemical and biological contaminants. Typically, such masks include a respiratory cup which fits over the user""s mouth and nose, and is secured to the user""s head. Such respiratory cups typically include a connection to an oxygen source, and a filter element containing a decontamination media for removing harmful substances from the air breathed in by the user.
However, this method suffers from several disadvantages. The usefulness of a respiratory mask only is dependent on the lifespan and efficiency of its filter element. Conventional decontamination filters are only useful for relatively short periods of time, i.e. 30 minutes or less, because there is a limit to the amount of decontamination media which they can hold. Thus, conventional decontamination filters are relatively inefficient, and frequently result in a relatively high pressure differential across the filter and the decontamination media of the filter. As a result, the use of very large quantities of decontamination media is the only satisfactory way in which to use these materials. However, the relative large pressure differential problem would still remain.
Thus, it would be desirable to devise a more efficient, higher capacity absorptive filter for the neutralization and/or decontamination of chemical and/or biological contaminants from a breathable atmosphere, which also provides a lower pressure differential. The present invention provides a solution to this problem.
According to the present invention, a filter for an individual, a vehicle, a room, a building, or the like, is provided which is formed from a plurality of polymeric multilobal fibers. These fibers include a central core having a plurality of T-shaped lobes projecting therefrom, with each T-shaped lobe having a leg and a cap. The lobes define a longitudinally extending internal cavity between two adjacent legs that extends the entire length of the fiber. The filter is impregnated with a biological and/or chemical decontamination reagent in an amount sufficient to chemically modify, neutralize, decontaminate, absorb, and/or adsorb airborne biological and/or chemical contaminants from a breathable atmosphere. The structure of the polymeric multilobal fibers allows the filter to hold more of the decontamination reagent than conventional filters can hold. This increases the removal capacity, affinity, and efficiency of the filter, and causes a lower pressure differential across the filter.
In another embodiment, the filter includes a wicking element which extends from the filter and extends into a reservoir which contains a supply of a biological and/or chemical decontamination reagent. The wicking element is capable of delivering the biological and/or chemical decontamination reagent from the reservoir to the filter, and replenishing the reagent consumed in the filter. Together, the wicking element and reservoir are capable of equilibrating the flow, level, and/or concentration of the biological and/or chemical decontamination reagent between the reservoir and the filter, thus extending the useful life of the filter and increasing its efficiency.
The invention provides an apparatus for chemically modifying, neutralizing and/or decontaminating chemical and/or biological contaminants from a breathable atmosphere, said apparatus comprising a filter which comprises a plurality of polymeric multilobal fibers, said fibers comprising a central core having a plurality of T-shaped lobes projecting therefrom, each of said T-shaped lobes having a leg and a cap, said lobes defining a longitudinally extending internal cavity between two adjacent legs that extends the entire length of the fiber; and which filter has been impregnated with at least one biological and/or chemical decontamination reagent in an amount sufficient to chemically modify, neutralize and/or decontaminate chemical and/or biological contaminants from a breathable atmosphere.
The invention also provides a self-regenerating filter system which comprises:
a) a filter which comprises a plurality of polymeric multilobal fibers, said fibers comprising a central core having a plurality of T-shaped lobes projecting therefrom, each of said T-shaped lobes having a leg and a cap, said lobes defining a longitudinally extending internal cavity between two adjacent legs that extends the entire length of the fiber; and which filter has been impregnated with at least one at least one biological and/or chemical decontamination reagent in an amount sufficient to chemically modify, neutralize and/or decontaminate chemical and/or biological contaminants from a breathable atmosphere;
b) a reservoir connected to the filter, which reservoir contains a supply of a biological and/or chemical decontamination reagent for replenishing the reagent of the filter;
c) a wicking element which extends from the filter into the reservoir and is capable of delivering a supply of a biological and/or chemical decontamination reagent from the reservoir to the filter; and
d) an optional activated carbon component connected to the filter, which activated carbon component is capable of chemically modifying, neutralizing and/or decontaminating chemical and/or biological contaminants from a breathable atmosphere.
The invention further provides a process for chemically modifying, neutralizing and/or decontaminating chemical and/or biological contaminants from a breathable atmosphere, comprising the steps of:
a) providing a filter which comprises a plurality of polymeric multilobal fibers, said fibers comprising a central core having a plurality of T-shaped lobes projecting therefrom, each of said T-shaped lobes having a leg and a cap, said lobes defining a longitudinally extending internal cavity between two adjacent legs that extends the entire length of the fiber; and which filter has been impregnated with at least one biological and/or chemical decontamination reagent in an amount sufficient to chemically modify, neutralize and/or decontaminate chemical and/or biological contaminants from a breathable atmosphere;
b) passing a breathable atmosphere through the impregnated filter to thereby chemically modify, neutralize and/or decontaminate chemical and/or biological contaminants from the breathable atmosphere; and
c) optionally passing the breathable atmosphere through an activated carbon component connected to the filter, which activated carbon component to thereby further chemically modify, neutralize and/or decontaminate chemical and/or biological contaminants from the breathable atmosphere.
The invention still further provides a process for chemically modifying, neutralizing and/or decontaminating chemical and/or biological contaminants from a breathable atmosphere, comprising the steps of:
i) providing a self-regenerating filter system which comprises:
a) a filter which comprises a plurality of polymeric multilobal fibers, said fibers comprising a central core having a plurality of T-shaped lobes projecting therefrom, each of said T-shaped lobes having a leg and a cap, said lobes defining a longitudinally extending internal cavity between two adjacent legs that extends the entire length of the fiber; and which filter has been impregnated with at least one biological and/or chemical decontamination reagent in an amount sufficient to chemically modify, neutralize and/or decontaminate chemical and/or biological contaminants from a breathable atmosphere;
b) a reservoir connected to the filter, which reservoir contains a supply of a biological and/or chemical decontamination reagent for replenishing the reagent of the filter;
c) a wicking element which extends from the filter into the reservoir and is capable of delivering a supply of a biological and/or chemical decontamination reagent from the reservoir to the filter; and
d) an optional activated carbon component connected to the filter, which activated carbon component is capable of chemically modifying, neutralizing and/or decontaminating chemical and/or biological contaminants from a breathable atmosphere;
ii) passing a breathable atmosphere through the impregnated filter and optionally through the activated carbon component, if present, to thereby chemically modify, neutralize and/or decontaminate chemical and/or biological contaminants from the breathable atmosphere;
iii) replenishing the reagent of the filter by equilibrating the flow, level, or concentration of the biological and/or chemical decontamination reagent between the reservoir and the filter via the wicking element; and
iv) optionally repeating steps (ii) and/or (iii) until the biological and/or chemical decontamination reagent of the reservoir has been exhausted.